====== Dopamine Agonist ======

A [[dopamine]] [[agonist]] is a compound that activates [[dopamine receptor]]s in the absence of [[dopamine]]. Dopamine agonists activate signaling pathways through the dopamine receptor and trimeric G-proteins, ultimately leading to changes in gene transcription.

[[Bromocriptine]]

[[Cabergoline]]

[[Pergolide]]



Dopamine agonists (DAs) are the first-line treatment for [[prolactinoma]]s. DAs primarily target the dopamine D2 receptor (D2R). 

[[Dopamine agonist]] therapy is the first line of treatment for [[prolactinoma]]s because of its effectiveness in normalizing serum [[prolactin]] levels and shrinking tumor size. Though withdrawal of dopamine agonist treatment is safe and may be implemented following certain recommendations, recurrence of disease after cessation of the drug occurs in a substantial proportion of patients. Concerns regarding the safety of dopamine agonists have been raised, but its safety profile remains high, allowing its use during pregnancy. Surgery is typically indicated for patients who are resistant to medical therapy or intolerant of its adverse side effects, or are experiencing progressive tumor growth. Surgical resection can also be considered as a primary treatment for those with smaller focal tumors where a biochemical cure can be expected as an alternative to lifelong dopamine agonist treatment. Stereotactic radiosurgery also serves as an option for those refractory to medical and surgical therapy
((Wong A, Eloy JA, Couldwell WT, Liu JK. Update on prolactinomas. Part 2:
Treatment and management strategies. J Clin Neurosci. 2015 Oct;22(10):1568-74.
doi: 10.1016/j.jocn.2015.03.059. Epub 2015 Aug 1. Review. PubMed PMID: 26243714.
)).
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From the beginning of the 20th century, acromegaly could be treated by pituitary surgery and/or radiotherapy. After 1970, medical therapies were introduced that could control acromegaly. First, [[dopamine agonist]]s were introduced, followed by somatostatin analogues and GH-receptor blockers.

They are efficient in less than 20% of non-irradiated [[acromegaly]] patients. They are a good cost-effective alternative for carefully selected patients
((Vandeva S, Elenkova A, Natchev E, Kirilov G, Tcharaktchiev D, Yaneva M,
Kalinov K, Marinov M, Hristozov K, Kamenov Z, Orbetzova M, Gerenova J, Tsinlikov 
I, Zacharieva S. Treatment Outcome Results from the Bulgarian Acromegaly
Database: Adjuvant Dopamine Agonist Therapy is Efficient in Less than One Fifth
of Non-irradiated Patients. Exp Clin Endocrinol Diabetes. 2015 Jan;123(1):66-71. 
Epub 2015 Jan 22. PubMed PMID: 25611123.)).
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Patients who are deemed dopamin agonist (DA) resistant or cannot tolerate DA treatment can be referred for surgery and less ideally radiosurgery. There is controversy over the length of DA treatment before declaring a patient resistant to therapy and exploring other options. While some patients do experience regression of their tumors only after a few months on DA therapy, longer duration of DA has been associated with increased fibrosis in the tumor, potentially making surgical treatment more difficult and risky
((Landolt AM, Osterwalder V (1984) Perivascular fibrosis in
prolactinomas: is it increased by bromocriptine? J Clin Endocrinol
Metab 58:1179–1183)).